Directive radio system



' Dec 17', I946. ODET 2,412,612

DIRECTIVE RADIO SYSTEM Filed Oct. 8, 1941 s Sheets-Sheet 1 Inventor: Sidneg Godet,

b x Wa 2W His AttoT-Tlgg.

Dec. 17, 1946. 5.60051" 2,412,612

DIBECTIVE RADIO SYSTEM Filed Oct. 8, 1941 3 Sheets-Sheet 2 Fig.2. Fig.3.

Fig. 4a. Fig. 4b. Fig. 4c.

Voltage between Voltage between Voltage between slip rings. train brushes. elevation brushes Target below axis of rotation.

Fig. 5a. Fig.5b. .FigSe.

Target above axis of rotation.

Fig. 7a. Fig. 7b. Fig. 7o.

Target left-of axis of rotation.

Fig. a Inventor:

' o l V kz\? degnees Sidney Godec,

V His Attorney.

S. GODET' DIRECTIVE RADIO SYSTEM 3 Sheets-Sheet. 3.

Filed Oct. 1941 Inventor: Sidheg Goclet Elli I an? 7 His Attorneymeme ne -17, 194s DIRECTIVE RADIO SYSTEM Sidney Godot, Schenectady, N. Y., asslgnor to General Electric Company, a corporation of New York Applicatlonqctober 8, 1941, Serial No. 414,126

14 Claims. 1

My invention relates to directive radio systems and in particular to means for controlling automatically the direction of orientation of said systems.

It has for one of its objects to provide means responsive to received waves to control the di-- rection of orientation of the receiving system in a plurality of planes to maintain said direction in correspondence with the direction of propagation of the received waves.

A further object of my invention is to provide means for automatically maintaining a directive radiating system directed at a moving object on which waves radiated by said system impinge.

A further object of my invention is to provide means for producing from received waves a cyclical variation corresponding in its time phase relation to the direction from which said waves are received together with means controlled by said time phase relation to operate in accordance with said direction,

Further objects of my invention relate to the provision of particularly efiicacious means for utilizing the time phase relation of said cyclically varying response to control the orientation of the receiving system.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings in which Fig. 1 represents an embodiment of my invention; Figs. 2, 3, 4, 5, 6, 7 and 8 represent certain characteristics thereof, and Fig. 9 represents a modification of my invention.

Referring to Fig. 1 of the drawings, I have shown in the upper right-hand corner thereof, in a very conventional way, a radio system which may comprise an antenna arranged within, as at the focal point of, a reflector I. This reflector I may comprise any conducting surface, preferably in the form of a surface of revolution. Commonly such reflectors are of a paraboloidal form having the antenna at the focal point thereof. This antenna, together with the reflector I may be considered to have a directivity pattern about an axis 2, this axis being the axis of directivity of the system. The reflector I, may suitably be mounted upon a shaft 3 arranged for rotation in a bearing 4, and such other bearings as may be required when driven by a motor arranged on the shaft. The axis 6 of the shaft 3 extends at an angle of a few degrees to the axis of directivity 2 of the antenna system and accordingly the axis of dlrectivity 2 is rotated about the axis 6 of the shaft 3, its path of revolution comprising the surface of a cone. Waves received from the direction of the axis 6 are, therefore, received with uniform intensity in all positions of the antenna system I in its rotation, except for such variations in intensity as may be produced by changes in the plane of polarization of the antenna. The effect produced by such variations will later be discussed. Waves received from any direction other than the direction of axis 6, however, affect the receiving antenna differently by reason of its different orientation when the system is atdifierent points in its path and the result is a periodically varying response of the antenna to such waves. This periodically varying response has a time phase relation dependent upon the direction from which the waves are received with respect to the direction of orientation 6 and, in accordance with my invention, this time phase relation is utilized to control the orientation of the system, that is, to control the direction of the axis 6 to maintain that axis directed along the line of propagation of the received waves.

This cyclical variation in response of the system to waves received from directions other than the direction of axis 6 may be produced either by rotating the reflector, the antenna, or both as desired. In systems where the reflector is too large it is preferable to rotate only the antenna. To vary the orientation the center of symmetry of the antenna may be rotated about the focus of the reflector without rotating the..antenna itself. For reasons of mechanical simplicity of the system, however, the antenna itself may also be rotated about its point of symmetry. This results in a cyclical variation in response due to changes in polarization of the antenna. This variation is not objectionable, however, since it is double the frequency of the rate of rotation of the antenna and its effect is automatically eliminated in the system presently to be discussed.

The shaft 3 is arranged for rotation about both the horizontal and the vertical axis. The bearing 6 is mounted upon a horizontal shaft 1, which is mounted for rotation in bearings 8, and which is provided with a gear sector 9, which cooperates with a gear l0 driven by a motor I l whereby upon operation of the motor I! the shaft 3 may be rotated in a vertical plane about the horizontal axis I thereby to project the axis of orientation 6; at any desired angle in the vertical plane.

The bearings 8. supporting the horizontal shaft 1, may be supported upon a horizontal ring gear l2, which cooperates with a gear l3 driven by a motor l4 whereby upon operation of the motor I4 the ring gear I2 is rotated in the horizontal plane thereby carrying the shaft 3 horizontally about a vertical axis which may be considered to comprise a shaft l6. Thus the antenna system may be directed in any direction in the horizontal plane.

The radio equipment associated with the antenna may be considered to be represented by the cube I'I shown on the drawings beneath the equipment thus far described. A transmission line extends from this equipment to the antenna of the system I, this transmission line being represented by a dotted line 8 on the drawings, and extends through the vertical shaft l6 into the horizontal 4 the commutator and which may be positioned, for example, in the horizontal plane.

In the operation of the system as thus described unidirectional potentials appear on condensers 33 and 34 having polarity and intensity dependent upon the direction from which the waves intercepted by the antenna system arrive. The potential on condenser 33 is supplied between the control electrodes 4| and 42 of a pair of electron discharge devices 43 and 44, the anode circuits of which include respective field windings 45 and 46 of a direct current generator 41, the potential of the latter of which is supplied to the motor ll,

'. which drives the antenna system in its orienta- 5| which include in their anode circuits the reshaft 1, thence through an interconnecting member l9 to the horizontal shaft 3 through which it passes to the antenna of the system I. These various shafts are hollow to enclose the transmission line l8. This line may comprise a central conductor, which may be considered as represented by the dotted line l8 and an outer conductor which is grounded.

Rotatable joints are provided at the left end of the shaft 3 and at the left end of the shaft l and at the bottom of shaft Hi to permit rotation of these respective shafts about their own axes.

Radio frequency potentials induced in the antenna are supplied through the transmission line 88 to radio equipment H where it is amplified, converted in frequency as desired, detected, and the resulting pulses of unidirectional current are supplied to a detector 2|. These unidirectional pulses may occur at a frequency of about 2000 cycles per second.

As previously described the current supplied to the detector 28, comprising these unidirectional pulses, may cyclically vary in intensity at a frequency corresponding to the frequency of rotation of the antenna system I. Thus, if the reiiector i be rotated at 20 revolutions per second the current supplied to the detector 2| is modulated at a 20 cycle rate. Thus a potential is produced upon the load resistance 22 and shunt condenser 23 of the detector 2| having a 20 cycle modulation. This 20 cycle modulation is supplied through a coupling condenser 24 and potentiometer 25 to the grid of an amplifier 26 where it is amplified and supplied through a transformer 2'0 to the control electrodes of a push-pull amplifier 28. The output potential from this pushpull amplifier 28 is supplied through a mechanical rectifier comprising slip rings 29 and 30 and commutator segments 3| and 32 to a pair of condensers 33 and 34.

This mechanical rectifier may be suitably mounted upon the shaft 3 for rotation therewith. The slip ring 29 may be considered to be connected to the commutator segment 32 and the slip ring 36 may be connected to the commutator segment 3| as indicated by dotted lines on the drawings, the two commutator segments being in the form of oppositely disposed semi-circles of a single circumference. The condenser 33 is connected-through choke coils 35 and 36 between a pair of brushes 3'! cooperating with the commutator segments 3| and 32, and which may be disposed, for example, in the vertical plane. Condenser 3 l is connected through choke'coils 38 and 39 between the brushes d0 cooperating with spective field windings 52 and 53 of a direct current generator 54, the voltage of which is supplied to the motor l4, which drives the antenna in its orientation in the horizontal plane.

For a more detailed understanding of the operation of the system as thus far described, let us refer to Figs. 2 to 7. Frequently apparatus, in accordance with my invention, may be employed in connection with echo systems in which waves are radiated from the antenna in the form of short pulses of but a few microseconds duration, these waves being propagated in sharp beams from the antenna system and being again received upon the antenna system after they are reflected from a remote reflecting surface. Such impulses may be also utilized to operate radio equipment upon remote aircraft, for example, which, in turn, transmit other impulses which may be received in the receiving system. Thus,

in such equipment, the apparatus represented by the cube ll may be considered as both a transmitter supplying the antenna system and as a receiver responding to waves intercepted by the antenna system.

The received radio frequency pulses are supplied through transmission line l8 to the equipment I! where they are detected to produce 3midirectional current pulses such as those represented at in Fig. 2. These pulses are then supplied to detector 2|. The intensity of these pulses may be considered to vary in a sine wave fashion when the direction from which said waves are received does not correspond with the direction of the axis 6, this sine wave variation having a frequency equal to the rate of rotation of the system This modulation of the pulses 60 is detected by the detector 2| to produce a unidirectional voltage upon the resistance 22 having a saw-tooth variation therein as indicated by the curve 3| of Fig. 3. This voltage 6| is amplified by the amplifier 26 and supplied through transformer 21 to the grids 62 and 63 0f the push-pull amplifier 28 in opposite phase. The transformer may be broadly tuned to the cyclic variation which may, for example, be of a frequency of 20 cycles per second and it eifectively removes the saw-tooth variation indicated in Fig. 3. The result is a sine wave of voltage existing between the anodes of the amplifier 28. This voltage may be considered as represented by the curve 64 of Fig. 4(a).

This voltage is then supplied through the mechanical rectifier, comprising the slip-rings 29 and 30, and the commutator segments 3| and 32 cooperating with two pairs of brushes 31 and 40, to the condensers 33 and 34, each of which is con' nectcd between a respective pair of said brushes.

The eflect or the mechanical rectifier is to reverse the pol ty of the alternating current wave supplied to each pair of brushes twice in each cycle 1 of the wave, the reversal occurring at the brushes 3'! being displaced by 90 degrees in the cycle from the reversals which occur at the brushes 40.

Thus, for example, if the voltage supplied between t the form represented by the curve 66 of Fig. 4(c).

The choke coils 35, 3B, 38 and 39 are of suiflciently great inductance substantially to remove the al- .ternating, or variation, component of the waves 65 'and 6G with the result that no voltage appears upon condenser 33, since the wave 65 is symmetrical with respect to the zero axis 67. A unidirectional voltage does appear upon condenser 34,

since the wave 66 is not symmetrical with respectto the zero axis, this voltage being represented by the distance between the dotted line 58 and the zeroaxis 69 of Fig. 4(c), this distance representing the average value of the wave 66. Thus condenser 34 assumes. a charge and accordingly one of the control grids 48, or 49, of the discharge devices 50 and 5| becomes more positive than the other, with the result that one of these devices 50 and 5| passes more current in its anode'circuit than the other. These anode currents flow from a source, the positive terminal of which is indicated at 10 through the two windings 52 and 53 of the generator 54 and the respective discharge devices 50 and 5! back to the negative terminal ll of the source. The result is that a voltage is produced by the generator 56 of a certain polarity which is supplied to the motor It, which in turn rotates the antenna system i in the horizontal plane to such a position that the voltage represented by the dotted lines 68 of Fig. 4(c) disappears.

The curves of Figs. 4(a) 4(b), and 4(0) may be considered to represent conditions which exist when the wave is received with maximum intensity from a direction in the vertical plane below the axis of orientation 6, for example.

If we assume that these waves are received from a source whose direction in the horizontal plane is to the right of the axis of orientation 6 of the antenna system then the corresponding voltage relations are those represented by the curves of Figs. 5(a) 5(1)) and 5(0) If the target be above the axis of rotation in-the vertical plane then the voltage conditions represented in Figs. 6(a), 6(b) and 6(0) exists, and similarly, if the waves are received :from a source whose direction in the horizontalpl'ane is to the left of the axis of rotation, then the voltage conditions will be those represented by Figs. 7(a), 7 (b) and 7(0).

It will be seen that when the wave is received from a source whose direction is to the right in the hcrizontal'plane a voltage represented by the dotted line 72 in Fig. 5(b) appears upon'the'condenser 33 and no voltage appears upon condenser 38. When it is received from a source. whose direction is above the axis of rotation in the vertical plane then no voltage appears upon condenser 33 but a voltage does appear upon condenser 34 as represented by the dotted line 13 in Fig. 6(0), this voltage being of opposite polarity from that indicated in Fig. 4(c) by the line 68 when the wave is received from a source whose direction is 6 below the axis. When the wave is received from a source whose direction is to the left of the axis of rotation a unidirectional potential appears upon condenser 33 as represented by the line Id of Fig. 7(1)), this voltage being of opposite polarity to that represented by the line 12 in Fig. 5(b). No voltage appears upon the condenser 34. It will thus be seen that the discharge devices 50 and 5lrespond to the unidirectional voltage on condenser 34 to control the direct current generator 54 to cause it to produce a unidirectional potential having an intensity dependent upon the projection of the angle between the direction 0! the source of the received waves and the axis of orientation 8 upon the horizontal plane and having a polarity determined by the direction of this angle from that axis in the horizontal plane.

' This voltage causes operation of the motor M in such a direction as to rotate the antenna system in the horizontal plane in a direction toward the direction of the source of the received waves.

Discharge devices 43 and M respond in a similar way to the voltage across condenser 33 to control the generator 31 to cause it to produce voltage which when supplied to motor ll causes it to rotate the antenna, system in the vertical plane in a direction toward the direction of the source of the received waves. In this way it will be seen that the direction of orientation 6 of the antenna system may be maintained directed automatically at the source of the received waves, which may be reflecting surface such as a remote aircraft upon which waves from the same antenna system impinge and from which they are reflected.

The direct current generators ll and 58 may of course be of any suitable type the voltage of which is controlled in intensity and polarity by field windings such as those shown at 45 and t6 and at 52 and 53, respectively. I prefer that these generators be of the type commonly known as Amplidynes.

Of course, in the operation of systems such as that here described the phenomenon of hunting is likely to occur, that is, for example, if voltage appears upon condenser 34 causing generator 55 to produce a voltage to drive the mo tor It in one direction, it may be that, due to inertia of the system and the like, the motor is does not stop when the voltage On condenser 36 disappears but continues and drives the antenna past the desired point, thereby producing a volt age of opposite polarity on the condenser 38. This in turn brings about a reversal of polarity of the voltage supplied by generator 5d to the motor it, which in turn reverses the direction of rotation of the antenna, which may, again, move too far, this hunting operation about the desired point continuing indefinitely. To counteract this eifect the voltage from the generator 53 is utilized through discharge devices 30 and M to modulate the screen grid potentials of the discharge devices 50 and 5| thereby'to change the conductivity of these devices in a direction opposite the change produced by the. potential on condenser 36. Similarly the voltage of the generator t! is utilized through. discharge devices 82 and 83 'to modulate the screen grid potentials of devices 63 and 4t. a

Each of the screen grids of discharge'devic'es 50 and Si, 53 and 44 have potentials supplied thereto from thepositive terminal --70 of the source through respective resistances 3t, 85, 85 and 81'. The voltage on resistance 86 is controlled by the current flowing between the anode and cathode of a discharge device 8I, the anode of this device being connected to the screen grid 68 of the device 59 and the cathode thereof being connected through a resistance .89 to the negative terminal II of the source of supply, In the same way the screen grid potential on the screen grid 99 of device is controlled by the current flowing in the anode circuit of. the discharge device 89. The control grid 92 01 the device 8I may be considered to be grounded by the moving contact 93 of a. switch having four armatures 93, 94, 95 and 96 and which are normally in the right-hand'position of the two positions shown on the drawings. The voltage generated by the generator 54 is supplied across apotentiometer 91 a portion of which issupplied between the control grids of the devices 89 and 8|, that is, between ground and the control grid I92 of the device 89. This circuit comprises the coupling condensers 98 and 99 and the armature 94 oi the switch in its right-hand position. The

condensers 98 and 99 are series condensers of an anti-hunt filter having a shunt branch comprising a resistance I 99 and an inductance I9I. The purpose of this filter will later be generally indicated but it is more particularly described and claimed in my copending application Serial No. 445,949 filed June 5, 1942, entitled Followup control system, and which is assigned to the same assignee as my present application.

Discharge devices 82 and 83 are associated with the voltage generator 41 and the discharge devices 43 and 44 in the same way that has been described in connection with the discharge ,de-

vices 89 and 8!.

For a more detailed description of the operation of these devices, let us assume the potential on condenser 94 i such that control grid at of device 5! i positive with respect to control grid 98 of device 59 and that the voltage of the generator 54 is of such polarity that the grid I92 of discharge device 89 is positive with respect to ground. Current increases in this device 89, this current flowing through resistances 85 and 99. The increase in current in resistance 85 reduces the potential applied between the screen grid and cathode of the device 5| thereby reducing the current flowing in the anode of that device. The potential on the resistance 89 tends to reduce the anode current in the device 8i which in turn increases the potential on the screen grid 88 of the device 59. These two ef- :fects thus both tend to restore the normal zero voltage of generator 54. Had the voltage of generator 54 been of the opposite polarity the opposite change of voltage would have occurred on the resistances 84 and 85, the change in voltage on resistances 84 and 85 always being in the proper direction to tend" to reduce the voltage of the generator 54 and thus to reduce the tendency to hunt.

The anti-hunt circuit comprising the elements 98, 99, M9 and I9! is designed to operate as a high pass filter, having output as low as possible below a frequency ,f (a) which is the highest fre-' quency of any component of motion of the reflecting surface from which impulses are received, and the motion of which the orientation of the antenna system is to follow, and having maxithe frequency at which hunting tends to occur;

The elements of the filter may have the following values:

Capacity Can of condenser 98 maybe Capacity C or condenser 99 maybe C inn/mi where R is the resistance of resistor 99' in ohms. L is the inductance of coil I9I in henries, and C98 and C99 are expressed in microi'arads, and f(b) is expressed in cycles per second. The value L of inductance. I9I may be arbitrarily chosen and the resistance oi. resistor I99 may best be determined empirically after the values L, Cos and C99 have been determined. The resistance of resistor 99' should be as high as possible.

It may be desired manually to control the orientation of the antenna system I. For this purpose armatures 94 and of the switch 93, 94, 95 and 96 are provided with alternate positions in which the circuits of the respective discharge devices 89 and 82 are disconnected from the anti-hunt circuit and connected to a bridge arrangement I95 from which voltage may be supplied to control manually the orientation of the system. This manual control device I95 comprises a potentiometer I96, which may be connected across a source of unidirectional potential. 'lhe grounded terminal of this potentiometer is connected to a variable contact. I91 on a circular bridge resistance comprising segments II9, III, I I2, and the variable contact I98 of potentiometer I96 is connected to a second variable contact I99 on the circular bridge resistance II9, III, H2. The latter'two contacts I91 and I99 are arranged for rotation in unison about the circular potentiometer comprising the three equal resistors II9, III and H2. These contacts I91 and I99 are positioned diametrically opposite each other on the circular resistances II9, III and H2 so that equal currents flow between these contacts through opposite portions of this circular resistance.

Three points H3, H4 and H5 between the equal segments II9, III, II2, of this circular potentiometer, are connected to respective points on a chain of resistances comprising resistors I I6, H1, H8, II9, I29 and I2I all connected in series in that order. The resistances H6 and I2I may be equal, resistances Ill and I29 may be equal, and H8 and [I9 may be equal. The discharge devices 82 and 83 which control the operation of the antenna in the vertical plane have their control grids connected for direct current respectively between the top and bottom points, that is, points H3 and I29 of the manual control device. The discharge devices 89 and 8| which control the operation of the system in the horizontal plane have their grids connected between points I22 and W3 symmetrically disposed with respect to these two points H3 and I24.

Let us suppose that movable contacts I91 and E99 are positioned vertically in the device. Then a potential exists between points II3 and I24, which potential is of polarity such that when supplied between the control grids of discharge devices 82 and 83 to control the potential of the screen grids of devices 43 and 44 it causes the generator 41 to supply voltage to-drive the antenna system in a certain direction in the vertical plane. The speed at which it is driven is controlled by variation of the position of contact I98 on the resistance I96. At this time no voltaeiaeia age exists between points I22 and 928 and accordingly no voltage exists between the grids 92 and. I02 of discharge devices 80 and 8| and the horizontal motor I6 is therefore not energized.

Now let ussuppose that the contacts I01 and I09 are both rotated in a clockwise direction through a quarter of its rotation; then no voltage exists between points I24 and H3 and the vertical driving motor II is deenergized. Voltage does exist between points I22 and I23 and hence between the control grids of devices 80 and 8|, which in turn operate through discharge devices 50 and I to cause the horizontal motor I0 to drive the antenna in the horizontal plane.

If contacts I01 and I09 be positioned at any other angle then both motors II and I0 are energized and operate to drive the antenna system at an angle both to the horizontal and the vertical. The speed at which the antenna system is driven is, of course, always controlled by the to I05, so long as this steady voltage, the value of which may be represented 'at M on Fig. 8, is less than the maximum value of the voltage of the generator produced in response to the received signal, 1. e, so long as the value M is less than the peak value of the curve V. The only diflerence is position of contact I08 on variable resistance I06.

It will be observed that voltage supplied from the manual control device I05 between the grids I02 and 92 of amplifiers 80 and 8| is supplied in series with voltage from potentiometer 91 produced by generator 54. Similarly, voltage supplied between control grids of devices 82 and 83 from device I05 is supplied in series with voltage from potentiometer I03. The action of the system is to maintain the sum of these two voltages substantially zero, i. e. the voltage from device I05 and the, voltage from the respective potentiometer. The feed back from the generator through the respective potentiometer to the input of the discharge devices is desirable to minimize any effect of residual magnetism in the respective generator, or unbalance in the circuit.

If, during the time when the antenna system is being oriented in response to manual adjustment of contacts I01 and I09 of device I05, a signal is received, as by reason of reflection from a remote surface such as an aircraft, the signal immediately seizes control of the apparatus and the orientation of the system follows the movement of the craft notwithstanding any potentials supplied from device I05. This is true if the orientation of the system agrees, within a few degrees, with the direction from which the received signal arrives.

The reason for this action of the device may better be understood from a consideration of Fig. 8. In Fig. 8 the curve V indicates the voltage of either of the generators 41 and 50 as the orientation of the antenna system is varied through the direction from which received waves arrived.

This curve is plotted with the magnitude of volt-.

age as ordinates and angle between the direction of orientation of the system and the direction of received waves as abscissa.

Let us assume that the system is oriented far to the left of the direction of the received signal. The voltage of the generator is then zero as indicated by the left end of the curve. As this orientation approaches the direction of the arriving signal the voltage ofv the generator first rises and then falls in accordance with the curve V until it becomes zero when the orientation of the system agrees with the direction from which the received signals arrive. Upon further movement of the system the voltage again increases and decreases until it becomes zero when the signal is no longer received.

This same eifect occurs if a steady voltage be produced by the generator in response to a steady voltage supplied from the manual controldevice his switch 93, 94, 95, 96 to the right-hand position.

That is, the operator uses the device I05 to scan remote. space until a remote source of received waves is found. The system then automatically orientates itself upon that source notwithstanding any manipulation of device I05. The operator then throws his switch 93 to 96 to the right for accurate orientation on that source.

Fig. 9 represents a modification of my invention in which the mechanical rectifier comprising the slip rings and commutator of Fig. 1 are replaced by electron discharge devices I30, I3I, I32 and I33 the anode circuits of which are supplied from respective output windings of Scott connected transformers I34 and I35,- the primary windings of which are energized in quadrature phase relation from a three-phase generator I30 mounted upon the shaft 3 of the radio system as in Fig. 1 and which has a frequency equal to the rate of rotation of the antenna system. The detector 2| and amplifiers -26 and 28 operate exactly as has been described in connection with Fig. 1 as do also the discharge devices 50, 5|, 43, 00 and'80 to 83.

Each of the discharge devices I 30, I3I, I32 and I33 comprises two triodes the grids of which are connected to opposite sides of the balanced output circuit of the amplifier 28. The cathodes of the discharge device I 30 are connected together and through a resistance I42 to ground. The

vice I30 are connected to opposite sides of the secondary winding of the transformer I34 as are also the anodes of devices I3I. Similarly the anodes of device I32'are connected to the opposite sides of the secondary windings with transformer I35 as are also the anodes of the device I 33.

It will be seen that the anodes of the two triodes in each of discharge devices I 30 and I3 I are alternately conducting at the same frequency as the modulation supplied through amplifier 26. Likewise the opposite triodes in the two devices I32 and I 33 are alternately conducting at the same frequency but in a time phase relation displaced by degrees from the periods of conductivity of the devices I 30 and I3 I Thus, for example, let us suppose that a sine wave ofvoltage of the 20 cycle frequency appears across the balanced output circuit of amplifier 28 and that this voltage is in phase with anode voltage on the upper anodes of the discharge devices I30, I3I. The potential on the grid I38 of amplifier I30 tends to cause the current in the anode circuit and in resistance I02 to increase. The voltage which is supplied from output circuit of amplifier 28 to the grid I39 is of the opposite phase 1 1 and tends to cause the current in the anode associated with grid I39 to reduce thereby reducing the current in resistance 3. The opposite grids I40 and I l! have no effect since the anodes of.

resistance M2 caused by a positive voltage on grid idil and a decrease in current in resistance I43 caused by a negative voltage on grid Hi.

The anodes of devices i322 and N3, however, are energized in 90 degree phase relation with respect to the devices ltd and fldi with the result that under the assumed conditions no voltage exists between the cathodes or upon condenser 3%. It the time phase relation, however, of the voltage. supplied by amplifier 28 shifts by so degrees, as would be the case if the direction of propagation of the received waves were rotated through 90 degrees about the axis of orientation of the antenna system, then the same situation would exist in devices use and 033 as has been described in connection with devices no and i351 and a voltage appears upon condenser The polarity of the voltage upon condensers 3t and it depends upon the phase relation between the voltage supplied from the balanced amplifier 28 and the anode voltage of the respective discharge devices and may be either positive or negative. Thus these devices operate as rectifiers to produce the unidirectional voltages varying exactly as has been described in connection with Fig. i.

The remaining portion of Fig. 9 is the same has been described in connection with Fig. 1 and requires no further description. Either the mechanical rectifier of Fig. 1 or the electron discharge rectifier of Fig. 9 has the advantage that the voltages produced on the condensers 33 and 34 are not affected by any even harmonics of the fundamental 20 cycle wave at the output of amplifier 28. This is desirable because the rotation of the antenna of the system I and the cyclical variation of its plane of polarization at twice the rate of rotation of the system I' produces such even harmonics to some appreciable extent. The rectifiers described, however, prevent their having any effect upon the operation of the system.

While I have shown particular forms of my invention, it will, of course, be understood that I do not wish to be limited thereto since various modifications both in the circuit arrangement and in the instrumentalities employed may be made, and I contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, a directive radio system, means to rotate said system about an axis extending at an acute angle to the axis of directivity of said system thereby to rotate said axis of directivity about said first axis, whereby waves received from a direction other than the direction of said first axis produce cyclically varying response in said system, a plurality of energy storage devices, a plurality of pairs of discharge devices, each storage device being connected between the cathodes of one of said pairs, means to supply alternating operating potential having 7 12 the frequency of said cyclical variation to the anodes of each pair in phase, the operating potential supplied to one pair being displaced by a predetermined angle from that supplied to another pair, means including said pairs of discharge devices to supply current varying as said cyclically varying response to each of said energy storage devices and to reverse the polarity of cur= rent supplied to each energy storage device at twice the frequency of said cyclical variation, the reversal of current supplied to one energy storage device being displaced by said predetermined angle from the reversals of the current supplied to the other device, and means responsive to potential developed in said storage devices to control the orientation of said first axis to maintain said potentials nil. 2. In a directive radio system, means to rotate the axis of directivity of said system about an axis of rotation extending at an acute angle -thereto, thereby to produce in said system cyclically varying response to waves received from directions other than the direction of said axis of rotation, said cyclically varying response hav ing a time phase relation dependent upon the direction of propagation of the received waves,

electron discharge means responsive to said cyclically varying response to produce a plurality of unidirectional electromotive forces, each electromotive force corresponding to a plane through said axis of rotation, and each having intensity and polarity dependent upon the projection of said direction of propagation upon a respective plane extending through said axis oi rotation, and means responsive to said electromotive forces to orient said axis of rotation in the direction of said propagation.

3. In a directive radio system, means to rotate the axis of directivity of, said system about an axis of rotation extending at an acute angle thereto, thereby to produce in said system a cyclically varying response to waves received from directions other than the direction of said axis of rotation, means responsive to said cyclically .varying response to orient said axis of rotation in a plurality of planes, said means comprising a pair of electron discharge devices corresponding to each plane, means to render said devices periodically conducting synchronously with said cyclic variation, the devices in each pair being conducting simultaneously and during periods displaced in time phase relation with respect to the periods of conductivity of the devices of another pair, means to vary oppositely the conductivity of the devices of each pair to an extent dependent upon the intensity of said cyclic variation while the respective devices are I conducting, and means responsive to the difference in the conductivity of the devices in each pair to control the orientation of said axis of rotation in the respective plane.

4. In combination, a directive radio system, means responsive to waves received in said system to control the orientation thereof, said means comprising a motor, means to supply voltage to said motor, and electron discharge means to control the polarity and intensity of said voltage, said electron discharge means comprising a pair of electron discharge devices, each of said devices having an anode, a cathode, a control electrode, and a second control electrode, means to vary the voltage on said first control electrodes differentially in response to the direction from which waves are received in said system, means to control said voltage supplied to said motor in retem'to control the orientation thereof in difierent planes, said means comprising a plurality of motors, means responsive to the direction of propagation of received waves to supply voltage to said motors of such intensity and polarity as to cause said motors to orient said system in said direction, and a single manual control member arranged for rotation, and means responsive to the position of said member in its rotation to vary the orientation of said system in any plane.

6. In combination, means to be oriented in different planes, a plurality of motors, each motor being arranged to orient said device in a corresponding one of said planes, a control device for said motors comprising a circular potentiometer having oppositely disposed contacts movable in unison about said circular potentiometer, a source of electromotive force connected between said gamers machine to produce a counteracting eflect on said I discharge devices.

9. In combination, a directive receiving system having an axis of orientation and having maximeans to separate said cyclical variation into two components corresponding to respective planes at right angles to each other, and means recontacts, an impedance loop having symmetrical-- 1y spaced points connected to corresponding points spaced about said circular potentiometer,

and means to control each of said motors in response to voltage between a respective pair of oppositely spaced points about said impedance loop, said points of one pair being displaced around the loop from the points of another pair.

7. In combination, a directive radio system,

I means responsive to waves received in said sys-.

tem to control the orientation thereof, said means comprising a motor, means to supp y voltage to said motor, and electron discharge means to control the polarity and intensity of said voltage, said electron discharge means comprising an electron discharge device having an anode, a

, cathode, and a pair of control electrodes, means to vary the voltage on one of said control electrodes in response to the direction from which waves are received in said system, means to control the voltage supplied to said motor in response to current in said discharge device, and means responsive to said voltage supplied to saidmotor to vary the potential on a second of said pair of control electrodes to counteract the effect produced by said voltage supplied to said first of said pair of control electrodes.

8. In combination, a radio system having maximum effect with respect to a particular direction, and having an axis of orientation extending at a small angle to said direction means to produce from waves received in said system an electromotive force varying in intensity and polarity sponsive to each of said components to operate in accord with the direction from which said waves are received in the respective planes.

10. In combination, a directive receiving system having an axis of orientation and having maximum sensitivity to waves received from a directive axis at a small angle to said axis of orientation, means to rotate said directive axis about said axis of orientation whereby waves received from a direction at an angle to said axis of orientation are received with cyclically varying intensity in said antenna, said cyclical variations in intensity having a time phase relation corresponding to the direction from which saidwaves are received relative to said axis of orientation, electron discharge means to produce a unidirectional electromotive force having polarity and intensitycorresponding to the projection of said direction on a. desired plane parallel to said axis of orientation, and means controlled by said unidirectional electromotive force to produce an effect when said electromotive force has one polarity and an opposite efiect when said electromotive force has the opposite polarity, said efiects varying with the magnitude of said unidirectional electromotive force.

11. In combination, a directive receiving sys-- tem having an axis of orientation and having maximum sensitivity to waves received from a directive axis at a small angle to said axis of orientation, means to rotate said directive axis about said axis of orientation whereby waves received from a direction at an angle to said axis of orientation are received with cyclically varying intensity in said antenna, said cyclical variations in intensity having a time phase relation corresponding to the direction from which said waves are received relative to said axis of orientation, means to detect said received waves to produce alternating electromotive force having alternating electromotive force a plurality of voltages each having variations corresponding duced by said last means on said dynamo electric machine to' vary said axis of orientation toward the direction from which said received waves arrive, and additional means responsive to said efiect produced on saiddynamo-electric to the projection of said direction on a corre-' sponding plane radiating from said axis of orientation, and means controlled jointly by said voltages to produce an efiect varying in accord with the direction of said projections on said planes.

12. In combination, a radio antenna having an axis of orientation and having maximum sensitivity to waves received from a direction at an angle to said axis, means to rotate said direction about said axis, means to detect the waves received in said antenna, whereby alternating electromotive force is produced having time phase relation dependent upon the direction from which said waves are received, a commutator having a commutator segment and slip ring and having oppositely disposed brushes alternately engaged by said segment, means to rotate said commutator segment and slip ring synchronously with rota-' tion of said direction of maximum effect, a capacitance connected between said brushes, and means to supply voltage varying in accord with said alternating electromotive force through said commutator to said capacitance, whereby a voltage is developed on said capacitance of magnitude and polarity corresponding to the projection of the direction from which said waves are received on a plane corresponding to the plane of said brushes.

13. In combination, an antenna having maxi mum sensitivity to waves received from a par-= ticular direction, means to rotate said direction about the surface of a cone, means to detect the received waves, whereby electrornotive force is produced varying cyclically in response to waves received from directions at an angle to the axis of said cone, a commutator having oppositely disposed brushes, a capacitance, means to supply said electromotive force through said commuta= tor and brushes to said capacitance, means to rotate said commutator synchronously with said direction, whereby said capacitance assumes a charge having polarity dependent upon the direction from which waves are received in a pre= determined plane corresponding to the plane of said brushes.

id. In combination, a directive receiving s37 tern having an axis of orientation and having maximum sensitivity to waves received from a directive axis at a small angle to said axis of orientation, means to rotate said directive axis about said axis of orientation whereby waves received from a direction at an angle to said axis of orientation are received with cyclically varying intensity in said antenna, said cyclical variations in intensity having a time phase relation corresponding to the direction from which said waves are received relative to said axis of orientation, two pairs of electron discharge devices, each having an anode, a cathode, and a control electrode, a resistance connected between the cathodes of one pair and the cathodes of the other pair, means to supply alternating operating potential having the frequency of said cyclical variations between an intermediate point on said resistance and said anodes, said voltage being supplied in opposite phase tothe anodes of each pair, means to supply voltage having said cyclical variations between the control electrodes of each pair, said last voltage being supplied between the control electrodes of one pair in opposite phase to that supplied between the control electrodes of the opposite pair, and means controlled by the voltage across said resistance to produce different efiects in accord with the polarity of said last voltage. 

